This study examines the hypothesis that autologous bone in the femoral tunnel for a hamstring anterior cruciate ligament (ACL) reconstruction will reduce femoral tunnel widening. Thirty-six patients undergoing hamstring autograft ACL reconstruction were randomized to 2 groups. One group underwent ACL reconstruction using EndoButton femoral fixation. The other group underwent the same procedure, with the addition of a bone plug placed at the aperture of the femoral tunnel next to the graft. Twenty-seven patients at > 6 months postoperatively (range, 6-12 months) had digitized anteroposterior (AP) and lateral radiographs of the involved knee. Tunnel widening was determined by comparing the radiographic tunnel diameters to the drilled tunnel diameters from surgery. The mean (+/- SD) tunnel enlargement on the AP radiographs in the standard and plug groups were 3.8 +/- 1.7 mm and 3.5 +/- 2.0 mm, respectively (P = .61). On lateral radiographic assessment, the mean (+/- SD) tunnel enlargement in the standard and plug groups were 3.3 +/- 1.9 mm and 3.4 +/- 2.2 mm, respectively (P = .90). Autologous bone plug graft during ACL reconstruction does not reduce femoral tunnel widening.